1. Field of the Invention
The present invention relates generally to window and patio door coverings or blinds, and, more particularly to coverings or blinds using vertical cellular fabrics.
2. Description of the Related Art
Vertical cellular blinds are known. Known vertical cellular blinds for patio doors, large windows and the like have a fixed vertical rail at one end and a movable vertical rail at the other end. It also is known to provide movable vertical rails at both ends of the blind. Cellular fabric is positioned between and connected to each vertical rail. Fabric-holding carriages are connected to the cellular fabric, and end carriages are connected to the movable vertical rail or rails. The carriages are suspended from a headrail, which also holds the fixed vertical rail if one is provided in place of one of the movable vertical rails. The movable vertical rail or rails can be adjusted in position relative to the overall length of the headrail between a fully closed position with the vertical rails positioned at the extreme opposite ends of the headrail and the fabric stretched there between, and a fully opened position with the fabric bunched tightly between the rails at one end or the other of the headrail. The movable vertical rail or rails can be positioned at any location between the maximum opened position and the maximum closed position so that a desirable area of the window or patio door there behind can be exposed.
It is known to use a cord or tape secured in the headrail and routed through the vertical rails and the fabric to provide stability to the fabric, and to promote straight orientation substantially parallel to the wall or patio door behind it. Due to the natural “springiness” of the cellular material, the blind may “creep” or move on its own from the position to which it is adjusted. The size of the blind and the characteristics of the fabric from which it is made affect the springiness and tendency for creep in the completed blind. For example, some relatively stiffer materials are used to improve light blocking, and the stiffer materials are springier than lighter materials used when light filtering is the desired effect. To overcome creep, frictional resistance is designed into the relative movement between the tape and fabric and/or between the tape and movable vertical rail to keep the blind in the desired adjusted position. However, excessive friction between the cord or tape and the fabric or movable vertical rail can make the blind difficult to traverse along the headrail between closed and opened positions. Additional force from the user is required to overcome the friction inhibiting relative movement between the blind structures and the tape or cord. It is known to provide user operable adjustments in the mechanisms establishing frictional resistance to relative movement between the tape and the blind structures. However, these can be difficult to adjust properly. Often, the blind is adjusted so that it is easy to operate but then suffers from creep. Alternatively, the mechanism can be adjusted to ensure that creep is inhibited by adjusting in a relatively high level of friction; however, the blind then can be difficult to operate.
Another inconvenience in known vertical cellular blinds is that the springiness of the cellular fabric can exert uneven forces against the vertical rails, particularly the movable vertical rail if one vertical rail is movable and the other is fixed. This can cause the vertical rail to hang from the headrail at an angle, in a non-true vertical position. An undesirable appearance can result.
Yet another inconvenience in known vertical cellular blinds is that some fabrics used therefor flex or create a wavy appearance when closed. Generally, the longer the shade, the more the wavy appearance that is created.
Still other inconveniences of known vertical cellular blinds are associated with the operation of the carriages and track assembly in the headrail. Carriages operating on the same track abut one against another even before the cellular fabric is fully compressed. Accordingly, the blind cannot be stacked or bunched as tightly as the fabric material would allow, because the carriages require more space for stacking than is required by the fabric suspended from the carriages. If carriages carrying the vertical rails are larger than the fabric panel carriages, the appearance of the closed blind is inconsistent, in that the center will bunch more tightly than the ends. Still further, it is known to connect the cellular fabric material relatively rigidly to the substantially rigid carriages. If the cellular fabric is accidentally pulled or tugged, the material can tear at the connections to the carriages from which it is suspended. Repair can be difficult and sometime unsightly.